As RUSS has a metallurgy qualification, he may well be aware of the use of zinc as a sacraficial anode on oil rigs, and anti-corrosion coating on buckets and wheel-barrows.
I am also similarly qualified, and as FORD are using these zinc parts, it is a clear admission that they recognise there is a corrosion problem. It is likely that road-salt is causing inter-granular corrosion in the windings of the springs.
It is common these days for springs to be plastic-coated.
Actually i'm in the aerospace industry so no idea about oil rigs!..............i have no idea how your springs are coated on your car but on my fiesta, my springs ARE plastic coated! and if Ford are zinc plating their springs then it's a new one on me. On any of the cars i`ve had to replace the springs on i've yet to see one that wasn't plastic coated! The posters complaint was his SPRING broke, not the 'cup' the spring sits in so it's the spring he is complaining about and not anything zinc plated!
Ford replace the CUP because when the spring breaks it falls down past the cup because the coils are larger than the outer diameter of the cup. This NEW cup then will ( i assume it is larger than the "old" cup ) stop the spring falling down the damper and causing the spring to rub against the wheel ( i again assume ) causing the grinding noise he heard.
Rust by the way doesn't make springs break! If that was the case then many peoples cars would be falling to bits as soon as anything under the car had a surface coating of rust on it. ( check your rear drums )
With regards to a clear admission there is a corrosion problem, i don't see how it's an admission? Using zinc to plate the replacement CUP
the SPRING sits in is to save Ford from painting the part after fitting it, nothing more. It saves them money!My point was .... springs break for various reason, just because a spring breaks does not mean there is a problem with the manufacturing of them. This is a forum and normally the only people who use a forum do so because they have a problem so how many people in the Ford Fiesta forum? How many who have had broken springs? And finally....how many thousand Fiesta's have been sold which so far haven't had broken springs and their owners are happy bunnys?
Before you can claim there is a manufacturing problem and seeing as 'some' don't trust Fords word for it, why don't they pay to get a 2nd opinion and if there is a manufacturing problem claim it back from Ford. Having actual proof that there is a defect will get you further in the end.